If a town becomes a city under this chapter, the town treasurer, if there is one, shall be the city treasurer. If there is no town treasurer, then the vacancy shall be filled by appointment by the circuit court having jurisdiction over the city or town, pending the next ensuing general election or, if the vacancy occurs within 120 days prior to such election, pending the second ensuing general election. The city treasurer, whether he is such by reason of having held the office of town treasurer or by appointment, shall not discharge any duties as city treasurer until he has given bond in a penalty to be fixed by the city council pursuant to § 15.2-1512 and also the bond required by § 15.2-1530. The treasurer so appointed shall qualify before the court appointing him. The treasurer’s duties shall include handling the city’s revenues from all sources as the council directs. He shall serve until his successor is elected and qualified.